A driver circuit for driving a semiconductor device is employed in all types of electric equipment and electronic equipment. As one example of the equipment, there is a power converter, e.g., an inverter for converting DC power supplied from a power supply to AC power, and supplying the AC power to an electric motor as a load. The driver circuit is made up of a plurality of circuit elements constituting a plurality of circuits, e.g., a circuit for generating a drive signal in accordance with an external command and a circuit for supplying drive power to the semiconductor device in accordance with the drive signal.
Hitherto, known driver circuits have been described, for example, in JP,A 5-316755 and “Hitachi High Withstand Voltage Monolithic IC Data Book-Motor Driving IC Series”, by Hitachi Ltd., March 2001, pp. 113-116. The driver circuits described in those documents are applied to power converters, and a plurality of circuit elements are built in the same semiconductor chip in the integrated form. In other words, a plurality of circuit elements are produced in the form of a monolithic IC (Integrated Circuit) or a SoC (System on Chip) IC.
By thus producing the driver circuit in the IC form, the following advantages are obtained as compared with the case constituting the driver circuit on a printed circuit board by using a large number of individual parts (discrete parts). Namely, (1) a noticeable reduction in both the number of parts and size can be realized, (2) an intelligent chip can be easily realized with addition of, e.g., protective and diagnosis functions, (3) a delay in signal transmission can be reduced because the plurality of circuit elements are integrated in the same chip, and (4) a noticeable reduction of the cost can be achieved with the mass production effect. Therefore, endeavors of producing the driver circuit for the power converter in the IC form have been positively promoted in the field of products where a smaller size, a lower production cost, and higher reliability are demanded for the power converter, e.g., in the field of automobiles where AC electric motors are used as drive sources of electric vehicles and hybrid vehicles.